Variable radius bending fixture

ABSTRACT

A MACHINE FOR BENDING LENGTHS OF TUBULAR OR ROD STOCKABOUT A BENDING DIE ASSEMBLY WHEREIN THE BENDING DIE IS COMPRISED OF A LENGTH OF CHAIN WOUND ABOUT A COMMON AXIS A SUFFICIENT NUMBER OF TIMES TO GENERATE THE REQUIRED RADIUS OF BEND IN THE STOCK.

W. A. OSTERLAND Feb. 23, 1971 VARIABLE RADIUS BENDING FIXTURE '2Sheets-Sheet 1 Filed Aug. 15, 1968 1971 w. A. OSTERLAND I ,8

VARIABLE RADIUS SENDING FIXTURE Filed Aug. 15, 1968 2 Sheets-Sheet 2ATTORNEY United States Patent 3,564,892 VARIABLE RADIUS BENDING FIXTUREWilliam A. Osterland, Aurora, 11]., assignor to Pines Engineering Co.,Inc., Aurora, 11]., a corporation of Illinois Filed Aug. 15, 1968, Ser.No. 752,972 Int. Cl. B21d 7/02 U.S. Cl. 72-219 Claims ABSTRACT OF THEDISCLOSURE A machine for bending lengths of tubular or rod stock about abending die assembly wherein the bending die is comprised of a length ofchain wound about a common axis a sufficient number of times to generatethe required radius of bend in the stock.

Bending machines generally comprise a frame upon one end of which ismounted a bending die having associated with it the usual clamp dies anda wiper die, the latter being movable about the axis of the bending dieto carry the work piece around said bending die for generating a bendtherein. With such machines, when a bend of a different bending radiusis to be performed, it is necessary to remove the bending die andreplace it with one having a different radius. This is time consumingand expensive especially in instances where but a few bends of a givenradii are required or when a plurality of pieces of stock are each to beformed with sevreal bends of different radii.

The present machine is provided with a bending die assembly which can beeasily and quickly changed from one radius to another withoutreplacement of the bending die. More specifically, the bending die ofthe present machine is comprised basically of a carrier plate or disc ofconsiderable diameter, having a core secured on its top surface aboutwhich a link chain or other flexible element is wound to generate thedesired working radius. Winding and unwinding of the chain isaccomplished by means of a motor geared to the bending die assembly andexcess chain is collected on a motor driven collector reel or spool. -Inorder to assure that the bend stock is devoid of markings which might begenerated thereon by the impression of the links of the chain, theeffective area of said chain is masked by a smooth bend. The bending dieassembly has, of course, associated with it the usual clamp dies and awiper die, the latter being effective to carry the stock around thebending die a requisite distance.

It is, therefore, an object of the invention to provide a bendingmachine with a variable radius bending die assembly.

Another object is to provide a bending die assembly of the character towhich referred.

Another object is to provide a bending die assembly of a character thatcan have the surface of its bending radius readily increased ordecreased.

Another object is to provide a bending die assembly of a characterhaving its bending surface comprised of a length of chain or the likewound thereon.

Another object is to provide a chain type bending die with a smooth workengaging surface.

Another object is to provide a variable radius bending die assembly ofthe character referred to which is not expensive or difficult tomanufacture, is easy to adjust, positive in its adjustment and veryefficient and satisfactory to use.

The structure by means of which the above noted and other objects andadvantages of the invention are attained will be described in thefollowing specification, taken in conjunction with the accompanyingdrawings, showing 3,564,892 Patented Feb. 23, 1971 a preferredillustrative embodiment of the invention, in which:

FIG. 1 is a plan view of a bending machine embodying the invention;

FIG. 2 is an enlarged plan view of the bending die assembly;

FIG. 3 is a detail sectional view taken substantially on line 33 of FIG.2, showing parts in elevation;

FIG. 4 is a detail sectional view of the take-up reel assembly, takensubstantially on line 4-4 of FIG. 2; and

FIG. 5 is a detail view of a fragment of the chain.

Referring to the exemplary disclosure of the invention as shown in theaccompanying drawings, the bending machine includes a base frame 11,upon which is mounted a suitable guide 12 for a workpiece 13 which maybe a length of tubular stock or rod stock. One end of the frame 11mounts on its top surface a bending die assembly generally indicated at14, associated clamp die assemblies 15 and 16, and a wiper die 17. Thewiper die 17 is carried on a fixture 18 that is rotatable about the axisof the bending die assembly so as to carry the workpiece 13 around thebending die, as shown in dotted lines in FIG. 2, a distance required toproduce the requisite bend therein.

It should be obvious that the radius of bend generated is determined bythe diameter of the bending die 14. Hence, in order to change the radiusof bend to be produced it is necessary to change the effective diameterof the bending die. This change is accomplished with ease by thedisclosed bending die assembly. This assembly is comprised essentiallyof a link chain 19, or other flexible member, wrapped around the axis ofthe bending die assembly a sufficient number of times to generate aneffective bending surface of the desired radius.

More particularly, the bending die assembly 14 is comprised of a carrierplate or disc 21 or relatively large diameter, about 48 inches, securedfirmly to a hub 22 that is journalled for free rotation about a studshaft sleeve 23 anchored firmly in the wiper die fixture 18 as by meansof a stud 24 having a retaining nut 25 threaded onto its upper end.Preferably, antifriction thrust bearings 26 are arranged between the huband stud sleeve.

The carrier plate 21 has a gear 27 secured to its bottom surface whichis meshed at all times with a pinion 28 carried on the upper end of ashaft 29 that is drivingly connected with a motor 31. Preferably, ahydraulic motor is used. This assembly provides drive means for rotatingcarrier plate 21 for a purpose to be explained presently.

The hub 22 carries, for rotation therewith and with the carrier plate, acore 32 that has a slightly eccentric outside diameter, as best shown inFIG. 2, and to which is connected one end of the link chain 19. Thischain, which is adapted to be wound on the core 32, as describedpresently, has its outwardly disposed surface ground down so as to berelatively smooth, as shown in detail in FIG. 5 at 33.

It should be apparent at this time that when motor 31 is operated torotate shaft 29, the chain is wound upon or unwound from core 32 so asto increase or decrease the number of turns thereon. By so doing, thereis presented a surface for the generation of a given radius of bend inthe work piece which is bent therearound. Because of the eccentricity ofcore 32, the chain winds thereon substantially concentrically. Tofacilitate visual determination of the radius generated by a givennumber of turns of the chain, the carrier plate 21 may have on its topsurface a series of indicies 34 in the form of circular lines eachbearing a radius marking.

The chain 19, which is of considerable length, has its other end securedto a rewind reel 35 mounted on frame 11 adjacent to the bending dieassembly. As best shown in FIG. 4, the reel 35 includes a gear 36 whichis 3 meshed with a pinion 37 carried on the end of the shaft 38 of amotor 39.

In operation, the radius of bend to be performed in a length of stock isdetermined and the motor 31 is operated to generate the number of turnsof chain to be cacumulated on core 32 to produce the required bend. Anyexcess chain is Wound upon reel 36. A surfacing band 41 (FIG. 2),adjustly anchored at its ends as at 42, 43, is laid over the wound chainon the bending die assembly to present a smooth work surface of thestock. The wiper die 17 then is swung around the bending die to carrythe stock over and against the surfacing band 41 to produce therequisite band. Of course it may be necessary to advance the wiper diebeyond the degree of bending required to compensate for spring back. Inany event, a number of like bends may be produced in succession, or, atwill, the radius of bend may be varied by winding or unwinding the chainto present more or less wrappings thereon and adjusting surface band 41.

Although I have described a preferred embodiment of my invention, inconsiderable detail, it will be understood that the description thereofis intended to be illustrative, rather than restrictive, as details ofthe structure may be modified or changed without departing from thespirit or scope of the invention. Accordingly, I do not desire to berestricted to the exact construction described.

I claim:

1. In a bending machine of the type including a bending die assembly,the improvement comprising a selfcontained adjustable bending die whichincludes a flexible element wound about an axial core a sufiicientnumber of turns to generate the effective bending diameter of thebending die, and means to wind and unwind said flexible element toselectively change the effective bending diameter of the bending die.

2. The bending machine of claim 1 wherein said axial core has aperipheral edge which is eccentric to cause the flexible element to windon the core substantially concentric with the axis of the axial core.

3. The bending machine of claim 1 wherein said bending die assemblyincludes a disc which carries said axial core on the upper surfacethereof whereby said flexible element rests on said upper surface of thedisc.

4. The bending machine of claim 3 in which the peripheral edge of theaxial core is concentric to cause the flexible element to wind thereonsubstantially concentric with the axis.

5. The bending machine of claim 1 in which the flexible elementcomprises a link chain wrapped around said axial core a suflicientnumber of turns to generate a bending radius of required dimensions.

6. The bending machine of claim 4 in which means is provided to rotatesaid axial core for collecting turns of chain thereon.

7. The bending machine of claim 5 in which a reel is provided to collectunused chain.

8. The bending machine of claim 7 including means to rotate the reel.

9. The bending machine of claim 5 in which a smooth strap is arrangedaround the wound chain.

10. The bending machine of chain 1 in which means are provided to rotatesaid axial core for collecting turns of said flexible element on saidaxial core.

References Cited UNITED STATES PATENTS 3,452,571 7/1969 Sassak 721573,181,331 5/1965 Wishing 72-319 2,659,411 11/1953 Bird 72--157 2,754,5807/ 1956 Schlaich 72-148 2,819,752 1/1958 Hart 72-157 5 CHARLES W.LANHAM, Primary Examiner .M. J. KEENAN, Assistant Examiner US. Cl. X.R.72-293, 157, 319

